5. The number of Protons plus the number
of Neutrons is the Atomic Weight
The number of Protons is the
Atomic Number
6. The negatively charged ELECTRONS are held in
their orbits by their attraction to the positively
charged PROTONS.
7. Electrons in the outermost shell are called
Valence Electrons
Valence Electrons that leave
the outermost shell are called
Free Electrons.
8. When an atom loses electrons it
becomes a positively charged Ion.
When an atom gains electrons it
becomes a negatively charged Ion.
The process by which atoms gain or
lose electrons is called Ionization.
9. Some materials hold their electrons very
tightly. Electrons do not move through them
very well. These things are called Insulators.
Plastic, cloth, glass and dry air are good
insulators.
Like aluminum, gold, silver and copper.
Other materials have some loosely held
electrons, which move through them very
easily. These are called Conductors. Most
metals are good conductors.
12. A basic law of the universe is that like charges
repel and unlike attract.
Two negatives will repel each other.
A negative and a positive will attract each other.
An electron has a negative charge.
The negative terminal of a battery will push
negative electrons along a wire.
The positive terminal of a battery will attract
negative electrons along a wire.
Electric current will therefore flow from the
negative terminal of a battery, through the lamp, to
the positive terminal.
14. COULOMB’S LAW
• Defination:-
Coulomb’s Law: The force of attraction or
repulsion between two point charges is directly
proportional to the product of the magnitude of
charges and inversely proportional to the square of
the distance between them.
15. • Explaination:
We know that a force of attraction or
repulsion acts between two charged bodies. a
French scientist Charles Coulomb (1736–
1806) in 1785 experimentally established the
fundamental law of electric force between two
stationary charged particles.
16.
17. Combining Equations (13.1) and (13.2),
we get
Substituting these values in Equation
(13.3), we have
Equation (13.3) is known as Coulomb’s
law.
18. • where F is the force between the two charges
and is called the Coulomb force,
• q1 and q2 are the magnitudes of two charges
and ‘r’ is the distance between the two
charges.
• k is the constant of proportionality.
• The value of k depends upon the medium
between the two charges.
19. • If the medium between the two charges is air,
then the value of k in SI units will be :
𝟗 × 𝟏𝟎 𝟗
𝑵𝒎 𝟐
𝑪−𝟐
• Coulomb’s law is true only for point charges
whose sizes are very small as compared to the
distance between them.
